Process of preparing indigoid vat dyestuffs



Patented Feb. 17, 1931 UNETEE STATES PATENT GFFECE ERWIN HUFFA AND WILHELM LUCE,OF HOCHST-ON-THE-MAIN, GERMANY, ASSIGNORS TO GENERAL A WGRKS, INQ, GE NEXV YORK, N, Y., A COB-EGRATION OF DELA- WARE PROCESS 6F PREPARING INDIGGID VAT DYESTUFFS No Drawing. Application filed January 26, 1928, Serial No. 249,765, and in Germany January 27, 1927.

The present invention relates to a new process of preparing vatwlyestuffs.

When arylthioglycollic acids are acted upon with phosphorus pentoxide a condensation will first take place with formation of hydronythionaphthenes. It is, however, difficult to obtain in the said manner hydroxythionaphthenes with a technically satisfactory yield because by the action of phos- 10 phorus pentorride or phosphoric acid upon hydroxythionaphthenes further condensations are caused.

lVe have now found that vat dyestuffs are obtained by treating with phosphorus pentoxide, a mixture of an arylthioglycollic acid and an ortho-diketone capable of being coupled and having the following general formula:

-C(1)CO -C(2)CO wherein X stands for S, N or a O-atom belonging to an aromatic ring and wherein the atoms C and 0 are members of an aromatic ring for instance isatin, acenaphthenequinone or the like or substitution prod ucts, homologues or analogues thereof. OW- ing to the fact that there occurs immediately a condensation with the said dilretones etc., the hydroxythionaphthenes which are formed as intermediate products are prevented from being further acted upon by the condensing agent.

It is advantageous to add to the phosphorus pentoXide a dispersing agent which keeps the condensing agent from sticking together, or the operations may be carried out in a solvent, which renders the phosphorus acid produced innocuous.

The following examples serve to lllustrate the invention, but they are not intended to limit it thereto, the parts being parts by weight:

(1) A mixture of 252, 5 parts of 1-chlornaphthalene-2-thioglycoll1c acid with 14:7 parts of isatin is dissolved in 3000 parts of dichlorobenzene while heating. To the hot solution is added a mixture of 300 parts of phosphorus pentoXide with 300 parts of silicic anhydride. The resulting mixture is kept boiling for half an hour whereupon the dyestul'l' which has formed is allowed to cool and then filtered by suction; it can be freed from the admixed silicic acid by treating it with a caustic soda solution. The dyestuif dyes the fiber from the Vat claret-red tints. It has probably the following formula:

(3) 216,5 parts of G-methyl-d-chlorphenyll-thioglycollic acid and 182 parts of acenaphthenquinone are dissolved while heating, in 5000 parts of chlorobenzene. After having added to the solution a mixture of 300 parts of phosphorus pentoXide and 300 parts of silicic anhydride the whole is boiled until the formation of the dyestuff is complete. After cooling, the resulting red Vatdyestulf is filtered by suction and purified in the manner indicated in Example 1. Instead of the free thioglycollic acid, there may also be used the corresponding quantity of its salts. The dyestuff obtained according to this example has probably the following formula CO\CTC I OH:

We claim:

1. The process which comprises subjecting an ar lthioglycollic acid having an unsubstituted ring carbon ortho to said acid group mixed with a condensahle o-diketone of the general formula:

C(2) CO wherein X stands for i S, N or a C-atom belonging to an aromatic ring and wherein the atoms C and C are members of an aromatic ring to the tion of phosphorus pentoxide in the presence of an indifferent organic diluent.

The process which comprises subjecting an arylthioglycollic acid having an unsubstituted ring carbon ortho to said acid group mixed with condensahle o-dikctone of the general formula:

wherein the atoms C 1 and C (2) are members 01 an aromatic ring to the action of phosphorus pentoxide in the presence of an indiii erent organic diluent.

3. The rocess which comprises subjecting an arylthioglycollic acid having an unsubstituted ring carbon orth to said acid group mixed with SI-dibromisatin to t re action oi phosphorus pentoxide in the presence of an indifferent organic diluent.

The process which comprises subjecting naphthalene-/3thioglycollic acid mixed with a condensable o-diketone of the general wherein X stands for S, l I or a C-atom belonging to an aromatic ring and wherein the atoms C and 0 members of an aromatic ring to the action of phosphorus pcntoxide in the presence of an indiiferentorganic diluent.

5. The process which comprises subjecting llu 

